Genuine OEM Detroit Diesel hydraulic pump drive coupling, part number 05135378. Fits Series 60 engines (11.1L / 12.7L / 14.0L) with rear gear train hydraulic pump drive. NOS (new old stock) condition in original packaging. Price is firm as listed unless “offers” enabled. Unsolicited discount requests will be ignored; repeated messaging may result in blocking. Honest mistake or fitment question? Message me first, happy to work it out!